The present invention relates to a method and apparatus for filling bottles, cans or similar containers with a prescribed quantity of a liquid material. The filling machine has a plurality of filling stations, each with a filling element having a liquid flow valve controlled by an actuating mechanism. The liquid flow valve is disposed in a liquid channel that forms a part of a material or product path and that has a dispensing or discharge opening via which the liquid material, during a filling phase with the liquid flow valve open, flows to a container that is positioned below the filling element. The filling machine also has an electrical control device that cooperates with the actuating mechanisms of the filling elements. To terminate a filling phase the control device delivers to a pertaining actuating mechanism a signal that effects closing of the liquid flow valve and that is a function of a measured value that is delivered by a flowmeter that is disposed in the product path, with the measured value corresponding to the quantity of material that has actually flowed to the container via the pertaining filling element, and with the control device also taking into consideration, for termination of the filling phase, the prescribed quantity of material that is to be dispensed into the container.
A method is known for filling bottles, cans or similar containers, i.e. for controlling an appropriate filling machine, from U.S. Pat. No. 4,557,301. With this known method, the dispensing of a prescribed quantity of filling material into bottles is controlled by associating a flowmeter with each filling station. This flowmeter delivers a measured value that is proportional to the quantity of material that has flowed to the respective bottle during the filling phase. This measured value is compared with a theoretical value in a control device. The filling phase is then terminated by closing the pertaining liquid flow valve if the measured value delivered by the flowmeter is equal to the setpoint value.
With this known method or filling machine, a flowmeter is associated with each filling element or filling section. This means that if a central control device is used, then in particular at a high output of the filling machine, a large amount of data is generated and must be processed in short time intervals. Such a central control device must therefore be designed to be extremely efficient. In addition to the already high cost that results from using a separate flowmeter for each filling station, an expensive central control device is therefore also necessary. In place of a central control device, it would also be possible to use a decentralized control for the individual filling elements by associating a separate control device with each filling element for the theoretical value/actual value control. However, this again means high cost due to the great capital outlay in control electronics. Furthermore, such a decentralized control makes it more difficult to input and/or take into consideration common parameters for improving or optimizing the filling process.
It is an object of the present invention to further improve a method and filling machine of the aforementioned general type in such a way that while maintaining the fundamental advantages of the prior art, it is possible to achieve a considerable reduction in the capital outlay for control purposes.